GMPartsGiant.com offers the wholesale prices for genuine 2003 GMC Sierra 2500 2WD parts. Parts like Automatic Transmission Overrun Clutch are shipped directly from authorized GM dealers and backed by the manufacturer's warranty. Parts fit for the following vehicle options. Engine: 8 Cyl 6.0L, 8 Cyl 6.6L Diesel, 8 Cyl 8.1L. Model Code: 2500 CREW CAB LONG BOX, 2500 CREW CAB STANDARD BOX, 2500 EXTENDED CAB LONG BOX, 2500 EXTENDED CAB STANDARD BOX, 2500 REGULAR CAB.